Question: $ B = \left[\begin{array}{rrr}0 & 2 & 2 \\ 2 & 1 & 0 \\ 1 & 1 & 1\end{array}\right]$ What is $ B^{-1}$ ?
Solution: $ = \left[\begin{array}{rrr}-\frac{1}{2} & 0 & 1 \\ 1 & 1 & -2 \\ -\frac{1}{2} & -1 & 2\end{array}\right]$